Surgical instrument with articulation assembly

ABSTRACT

A surgical instrument includes an elongate body, a toothed rack, and an end effector. The elongate body has a proximal end and a distal end and defines a first longitudinal axis. The toothed rack is disposed within the elongate body and is movable in a direction parallel to the first longitudinal axis. The end effector has a proximal end pivotally supported on the distal end of the elongate body. The end effector defines a second longitudinal axis and supports a gear operatively associated with the rack. Longitudinal movement of the rack effects pivotal movement of the end effector relative to the elongate body from a first position to a second position. In the first position, the second longitudinal axis is aligned with the first longitudinal axis. In the second position, the second longitudinal axis is misaligned with the first longitudinal axis.

BACKGROUND

Technical Field

The present disclosure relates generally to surgical instruments forendoscopic use and, more specifically, to surgical instruments havingarticulation assemblies for articulating an end effector of the surgicalinstrument.

Background of Related Art

Various types of surgical instruments used to endoscopically treattissue are known in the art, and are commonly used, for example, forclosure of tissue or organs in transection, resection, anastomoses, forocclusion of organs in thoracic and abdominal procedures, and forelectrosurgically fusing or sealing tissue.

One example of such a surgical instrument is a surgical staplinginstrument. Typically, surgical stapling instruments include an endeffector having an anvil assembly and a cartridge assembly forsupporting an array of surgical staples, an approximation mechanism forapproximating the cartridge and anvil assemblies, and a firing mechanismfor ejecting the surgical staples from the cartridge assembly.

During laparoscopic or endoscopic surgical procedures, access to asurgical site is achieved through a small incision or through a narrowcannula inserted through a small entrance wound in a patient. Because oflimited area available to access the surgical site, many endoscopicinstruments include mechanisms for articulating the end effector of theinstrument in relation to a body portion of the instrument to improveaccess to tissue to be treated.

A need exists for an improved surgical instrument, which includes amechanism for articulating the end effector relative to the body portionthat is easy to operate and is capable of positioning an end effector ina variety of orientations.

SUMMARY

In one aspect of the present disclosure, a surgical instrument isprovided. The surgical instrument includes an elongate body, a toothedrack, and an end effector. The elongate body has a proximal end and adistal end. The elongate body defines a first longitudinal axis. Therack is disposed within the elongate body and is movable in a directionparallel to the first longitudinal axis. The end effector has a proximalend and a distal end. The proximal end is pivotally supported on thedistal end of the elongate body. The end effector defines a secondlongitudinal axis and supports a gear operatively associated with therack. Longitudinal movement of the rack effects rotational movement ofthe gear to effect pivotal movement of the end effector relative to theelongate body from a first position to a second position. In the firstposition, the second longitudinal axis is aligned with the firstlongitudinal axis. In the second position, the second longitudinal axisis misaligned with the first longitudinal axis.

In some embodiments, the surgical instrument may further include anothergear rotatably supported at the distal end of the elongate body. Thegear supported on the elongate body may be defined as a first gear andthe gear supported on the end effector may be defined as a second gear.The first gear may be in meshing engagement with the rack and the secondgear such that the first gear converts longitudinal movement of the rackinto rotational movement of the second gear.

It is contemplated that the first gear may include a bottom gear and atop gear. The bottom gear may be in meshing engagement with the rack.The top gear may be non-rotatably coupled to the bottom gear and inmeshing engagement with the second gear. The bottom gear may be coplanarwith the rack and the top gear may be coplanar with the second gear. Thebottom and top gears of the first gear may be spaced from one another.The bottom gear may have a smaller diameter than a diameter of the topgear.

It is envisioned that the end effector may be configured to rotate 180degrees relative to the elongate body about a pivot axis extendingperpendicularly relative to the first longitudinal axis.

In some embodiments, the surgical instrument may further include anarticulation mechanism coupled to the proximal end of the elongate body.The articulation mechanism may include a lever operatively coupled to aproximal end of the rack such that rotation of the lever effectslongitudinal movement of the rack.

In some embodiments, the surgical instrument may be a surgical staplinginstrument.

BRIEF DESCRIPTION OF THE DRAWINGS

Surgical instruments including embodiments of the presently disclosedarticulation mechanism are disclosed herein with reference to thedrawings, wherein:

FIG. 1A is a perspective view of a surgical stapling instrumentincluding an embodiment of the articulation mechanism in accordance withthe present disclosure;

FIG. 1B is a perspective view of another surgical stapling instrumentincluding an embodiment of the articulation mechanism in accordance withthe present disclosure;

FIG. 2 is a perspective view of a loading unit of the surgical staplinginstruments of FIGS. 1A and 1B;

FIG. 3 is an enlarged view of the area of detail indicated by the number“3” in FIG. 2;

FIG. 4 is a perspective view of the loading unit of FIG. 2, with anouter housing and an upper half of an inner housing removed;

FIG. 5 is an enlarged view of the area of detail indicated by the number“5” in FIG. 4;

FIG. 6 is an exploded view of the loading unit of FIG. 2, with an outerhousing and an upper half of an inner housing removed;

FIG. 7 is a top view of a portion of the loading unit of FIG. 2illustrating the articulation assembly with an end effector of theloading unit shown in phantom in a first, non-articulated position;

FIG. 8 is an enlarged view of the articulation assembly of the loadingunit of FIG. 7 illustrating a proximal portion of the end effector shownin phantom in a second, articulated position approximately 90 degreesfrom the non-articulated position on one side of a longitudinal axis ofthe loading unit;

FIG. 9 is an enlarged view of the articulation assembly of the loadingunit of FIG. 7 illustrating a proximal portion of the end effector shownin phantom in a third, articulated position approximately 90 degreesoffset from the first, articulated position on the other side of thelongitudinal axis of the loading unit; and

FIG. 10 is a perspective view of the loading unit of FIG. 2 illustratingthe end effector in the third, articulated position.

DETAILED DESCRIPTION

Persons skilled in the art will understand that the instruments andmethods specifically described herein and illustrated in theaccompanying drawings are non-limiting exemplary embodiments. It isenvisioned that the elements and features illustrated or described inconnection with one exemplary embodiment may be combined with theelements and features of another without departing from the scope of thepresent disclosure. As well, one skilled in the art will appreciatefurther features and advantages of the disclosure based on the describedembodiments. Accordingly, the disclosure is not to be limited by whathas been particularly shown and described, except as indicated by theappended claims.

As used herein, the term “distal” refers to that portion of theinstrument which is farthest from a clinician, while the term “proximal”refers to that portion of the instrument which is closest to theclinician. In addition, as used herein, the term clinician refers tomedical staff including doctors, nurses and support personnel.

The present disclosure is directed to an articulation assembly forarticulating an end effector of a surgical instrument relative to anelongate portion of the surgical instrument. The articulation assemblyincludes a toothed rack and a gear non-rotatably coupled to the endeffector. The toothed rack is in operative association with the gearsuch that longitudinal movement of the toothed rack effects articulationof the end effector relative to the elongate portion, as will describedin further detail below. Additional advantages of the presentlydisclosed articulation assembly and surgical instruments including thepresently disclosed articulation assembly are described below.

FIGS. 1A and 1B illustrate surgical stapling instruments incorporatingembodiments of the presently disclosed articulation assembly, referencedgenerally as surgical stapling instruments 10 a and 10 b, respectively.Each of the surgical stapling instruments 10 a and 10 b can be used withthe same surgical loading unit 100. The depicted surgical staplinginstruments 10 a, 10 b fire staples, but may be adapted to fire anyother suitable fastener such as clips and two-part fasteners.Additionally, while the figures depict a linear surgical staplinginstrument, it is envisioned that the presently disclosed articulationassembly is suitable for use with other types of endoscopic surgicalinstruments including endoscopic forceps, graspers, dissectors, othertypes of surgical stapling instruments, powered vessel sealing and/orcutting devices, etc.

Generally, the surgical instrument 10 a includes a handle assembly 20including a movable handle 22, an endoscopic body portion 30 extendingdistally from the handle assembly 20, and a surgical loading unit 100disposed adjacent a distal end 32 of the endoscopic body portion 30. Theloading unit 100 includes an elongate body 102 and an end effector 110supported on a distal end 102 b of the elongate body 102. In someembodiments, the end effector 110, including a cartridge 112 and ananvil 114, does not form part of a loading unit 100, but rather, isdirectly coupled to the distal end 32 of the endoscopic body portion 30.As described above, the end effector 110 may include forceps, graspers,vessel sealing devices, etc., rather than a cartridge and anvilassembly.

As known in the art, the movable handle 22 is actuatable (e.g., throughone or more strokes) to cause distal advancement of a drive rod (notshown), such that the drive rod engages a portion of a drive assembly(not shown), which forces at least a portion of the drive assembly totranslate distally. Further details of how actuation of the movablehandle 22 causes distal advancement of the drive rod are explained inU.S. Pat. No. 6,953,139 to Milliman et al., the entire contents of whichare incorporated by reference herein. Distal movement of the driveassembly, and in particular, a dynamic clamping member affixed thereto,causes an actuation sled (not shown) to move distally through thecartridge 112, which causes cam wedges (not shown) of the actuation sledto sequentially engage pushers (not shown) to move pushers verticallywithin retention slots and eject fasteners towards the anvil 114.Subsequent to the ejection of fasteners from the retention slots (andinto tissue), a knife assembly 180 (FIG. 6) supported on the dynamicclamping member severs the fastened tissue as a knife 182 of the knifeassembly 180 travels distally through a slot defined by the cartridge112.

The surgical instrument 10 a also includes an articulation mechanism 40for articulating an articulation assembly 130. The articulation assembly130 is connected to the end effector 110 to facilitate articulation ofthe end effector 110, as described in detail below.

In embodiments, the articulation mechanism 40 includes a lever 42supported on a rotation knob 44 adjacent the handle assembly 20. Thelever 42 is adapted to actuate the articulation assembly 130 (FIG. 5),which is disposed within the loading unit 100, as will be described infurther detail below. In the illustrated embodiment, the articulationlever 42 of the articulation mechanism 40 is disposed on the rotationknob 44 of the surgical stapling instrument 10 a. However, it isenvisioned that the articulation lever 42 of the articulation mechanism40 may be located on or adjacent another portion of the handle assembly20.

The lever 42 of the articulation mechanism 40 is connected to a driveshaft (not shown). The lever 42 is rotatably coupled to the rotationknob 44 and is in operative association with the drive shaft such thatrotation of the lever 42 relative to the knob 44 results in linearmotion of the drive shaft. The drive shaft of the articulation mechanism40 is operatively coupled to an articulation shaft 132 of thearticulation assembly 130 of the loading unit 100 such that linearmovement of the drive shaft causes linear movement of the articulationshaft 132. Details of an articulation mechanism 40 suitable for causinglinear movement of a drive shaft to cause corresponding linear movementof articulation shaft 132 is disclosed in U.S. Pat. No. 6,953,139 toMilliman et al., which has been incorporated by reference herein.

The presently disclosed articulation assembly 130 is also suitable foruse with the surgical stapling instrument 10 b (FIG. 1A). The surgicalstapling instrument 10 b is an electromechanical device and includes anactuation button 42′, instead of a manually operable lever 42, to effectarticulation of the end effector 110. The actuation button 42′ is inelectrical communication with a motorized drive shaft (not shown), whichis operatively coupled to the articulation shaft 132 of the articulationassembly 130 such that actuation of the actuation button 42′ causes themotorized drive shaft to move linearly to cause linear movement of thearticulation shaft 132, as will be described in further detail below.

With reference to FIGS. 2-6, the loading unit 100 is adapted to beattached to the endoscopic body portion 30 of the surgical staplinginstrument 10 a (or 10 b) of the present disclosure. The loading unit100 may be configured for a single use, or may be configured to be usedmore than once and includes the elongate body 102, the end effector 110pivotally supported on the distal end 102 b of the elongate body 102,and the articulation assembly 130. As mentioned above, it is envisionedthat the end effector 110 may be pivotally coupled directly to theendoscopic body portion 30 of the surgical stapling instrument 10 arather than form a part of a loading unit.

In the illustrated embodiment, the elongate body 102 of the loading unit100 has a proximal end 102 a and a distal end 102 b and defines a firstlongitudinal axis “X1” between the proximal and distal ends 102 a and102 b, respectively. The proximal end 102 a of the elongate body 102 isremovably received within the distal end 32 (FIG. 1A) of the elongatedbody portion 30 of the surgical stapling instrument 10 a using, e.g., abayonet or luer type coupling. The elongate body 102 includes an outerhousing 104 and an inner housing 106 disposed within the outer housing104. The inner housing 106 houses, inter alia, the knife assembly 180(FIG. 6) and components of the articulation assembly 130. The outerhousing 104 may be in the form of a tube that covers the inner housing106 to prevent contaminants from contacting components disposed withinthe inner housing 106. In some embodiments, the elongate body 102 of theloading unit 100 may be integrally connected to or monolithically formedwith the endoscopic body portion 30 of the surgical stapling instrument10 a.

With reference to FIG. 3, the end effector 110 of the loading unit 100defines a second longitudinal axis “X2” that is aligned with the firstlongitudinal axis “X1” of the elongate body 102 when the end effector110 is in a first, non-articulated position, and is misaligned with thefirst longitudinal axis “X1” of the elongate body 102 when the endeffector 110 is in a second, articulated position, as described ingreater detail below. The end effector 110 has a proximal end 116pivotally coupled to the distal end 102 b of the elongate body 102. Inparticular, the proximal end 116 of the end effector 110 has a pivot pin118 that is received in openings 119 formed in upper and lower bridgemembers 120 that pivotably connect the end effector 110 to the elongatebody 102 (only the upper bridge member 120 is shown). The bridge members120 have a first end fixedly connected to the distal end 102 b of theelongate body 102 and a second end pivotably secured to the proximal end116 of the end effector 110 by the pivot pin 118. In some embodiments,other pivotable connections between the end effector 110 and theelongate body 102 are contemplated, such as, for example, a ball andsocket connection. The proximal end 116 of the end effector 110 definesa slot 122 that is dimensioned to slidably receive a distal end of thearticulation shaft 132 of the articulation assembly 130. The distal endof the articulation shaft 132 is connected to the end effector 110 suchthat as the shaft 132 moves from a retracted position to an advancedposition, the end effector 110 is articulated in relation to theelongate body 102, as described in detail below.

With reference to FIGS. 3-6, the articulation assembly 130 of theloading unit 100 includes an articulation shaft 132, a first gear 142,and a second gear 152, each being in operative association with oneanother. The articulation shaft 132 has a distal end that defines atoothed rack 134. The shaft 132 has a proximal end 132 a and a distalend 132 b and is movably disposed within a cutout 135 (FIG. 6) definedlongitudinally along the inner housing 106 of the elongate body 102. Thearticulation shaft 132 moves in a direction that is parallel to andlaterally offset from the first longitudinal axis “X1” of the elongatebody 102. The proximal end 132 a of the articulation shaft 132 isconfigured to engage a distal end of the drive shaft (not shown) of thearticulation mechanism 40 such that linear translation of the driveshaft causes linear translation of the articulation shaft 132. Thedistal end 132 b of the articulation shaft 132 defines the rack 134 andhas a plurality of teeth 134 a oriented inwardly toward the firstlongitudinal axis “X1.”

The first gear 142 of the articulation assembly 130 is rotatablysupported at the distal end 102 b of the elongate body 102 of theloading unit 100 and includes a bottom gear 142 a and a top gear 142 b.The bottom gear 142 a is positioned adjacent the slot 122 defined in theproximal end 116 of the end effector 110. The top gear 142 b isnon-rotatably coupled to and spaced from the bottom gear 142 a along apost 144. In some embodiments, the bottom and top gears 142 a, 142 b maybe in the form of pinion gears. It is envisioned that the bottom and topgears 142 a, 142 b may be in the form of various types of gears, suchas, for example, helical gears, miter gears, worm gears, anti-backlashgears, bevel gears, cluster gears, differential end gears, compositespur gears, and other gears known in the art. The inner housing 106 mayinclude a projection or pin (not shown) for rotatably supporting thebottom gear 142 a. The bottom gear 142 a has a perpendicularly extendingpost 144 that is received within a central opening 146 defined throughthe top gear 142 b to form a friction fit connection between the bottomand top gears 142 a, 142 b. In some embodiments, the bottom and topgears 142 a, 142 b may be non-rotatably coupled to one another viavarious fastening engagements, such, as for example, adhesives, welding,threads, key/slot arrangement, etc. Alternately, the bottom and topgears 142 a, 142 b may be monolithically formed.

The bottom gear 142 a is coplanar and in meshing engagement with therack 134 of the articulation shaft 132 adjacent the slot 122 defined inthe proximal end 116 of the end effector 110 such that longitudinalmovement of the articulation shaft 132 effects rotation of the bottomgear 142 a, and thus rotation of the top gear 142 b. In embodiments, thebottom gear 142 a has a smaller diameter than the diameter of the topgear 142 b. As such, as the first gear 142 rotates, a toothedcircumferential edge 148 of the top gear 142 b rotates at a greatervelocity than a toothed circumferential edge 150 of the bottom gear 142a.

The second gear 152 of the articulation assembly 130 is non-rotatablysupported at the proximal end 116 of the end effector 110 such that theend effector 110 rotates with the second gear 152 upon rotation of thesecond gear 152. The second gear 152 has a semi-circular configurationand is coplanar with the top gear 142 b of the first gear 142 of theelongate body 102. The second gear 152 has a toothed circumferentialedge 154 in meshing engagement with the toothed circumferential edge 148of the top gear 142 b of the first gear 142 such that linear advancementof the articulation shaft 132 causes rotation of the bottom and topgears 142 a, 142 b of the first gear 142, which causes rotation of thesecond gear 152. As described above, rotation of the second gear 152causes corresponding rotation of the end effector 110 about the pivotpin 118.

With reference to FIGS. 7-10, prior to actuation of the actuationmechanism 40 (FIG. 1A) of the surgical instrument 10 a or 10 b, the endeffector 110 is in a first, non-articulated position relative to theelongate body 102, as shown in FIG. 7. In this position, the firstlongitudinal axis “X1” of the elongate body 102 of the loading unit 100is aligned (i.e., parallel) with the second longitudinal axis “X2” ofthe end effector 110 to define an angle of 180 degrees betweenlongitudinal axes “X1” and “X2.”

To articulate the end effector 110 relative to the elongate body 102 ina clockwise direction toward a second, articulated position, the lever42 (FIGS. 1A, 1B) of the articulation mechanism 40 of the surgicalstapling instrument 10 a (or 10 b) is rotated clockwise. As describedabove, clockwise rotation of the lever 42 causes movement of thearticulation shaft 132 along the longitudinal axis “X1,”in a proximaldirection indicated by arrow “A” in FIG. 8. Linear motion of the shaft132, in the direction indicated by arrow “A,”is converted intorotational motion of the first gear 142, in a direction indicated byarrow “B” in FIG. 8, due to the meshing engagement of the bottom gear142 a of the first gear 142 with the teeth 134 a of the rack 134. As thebottom gear 142 a rotates, the top gear 142 b of the first gear 152 alsorotates. As described above, the top gear 142 b is in meshing engagementwith the second gear 152, which is secured to the end effector 110. Assuch, rotation of the first gear 142 causes rotation of the second gear152, in a direction indicated by arrow “C” in FIG. 8. In this way, thefirst gear 142 converts longitudinal movement of the articulation shaft132 into rotational movement of the second gear 152.

Rotation of the second gear 152 causes the end effector 110 to pivot orarticulate about a pivot axis “P” (FIG. 5), extending perpendicularlyrelative to the first longitudinal axis “X1,”due to the second gear 152being non-rotatably coupled to the proximal end 116 of the end effector110. Upon pivotal movement of the end effector 116 about the pivot axis“P,” the second longitudinal axis “X2” of the end effector 110 becomesmisaligned (i.e., non-parallel) with respect to the first longitudinalaxis “X1” of the elongate body 102, as shown in FIG. 8. Continuedrotation of the second gear 152 will continue to pivot the end effector110 until the respective longitudinal axes “X1” and “X2” of the elongatebody 102 and the end effector 110 are perpendicular to one another, asshown in FIG. 8. It is contemplated that the end effector 110 may bepivoted or articulated relative to the elongate body 102 to a positionin which longitudinal axes “X1” and “X2” define an angle greater than 90degrees.

To articulate the end effector 110 relative to the elongate body 102 ina counter-clockwise direction toward a third, articulated position, thelever 42 (FIG. 1A) of the articulation mechanism 40 is rotatedcounter-clockwise. Upon counter-clockwise rotation of the lever 42, thearticulation shaft 132 of the articulation assembly 130 moves along thelongitudinal axis “X1,” in a distal direction indicated by arrow “D” inFIG. 9. Linear motion of the articulation shaft 132, in the directionindicated by arrow “D,” is converted into rotational motion of the firstgear 142, in a direction indicated by arrow “E” in FIG. 9, due to themeshing engagement of the bottom gear 142 a of the first gear 142 withthe teeth 134 a of the rack 134. Rotation of the first gear 142 resultsin rotation of the second gear 152, in a direction indicated by arrow“F” in FIG. 9, via the meshing engagement between the top gear 142 b ofthe first gear 142 and the second gear 152. In this way, the first gear142 converts longitudinal movement of the articulation shaft 132 intorotational movement of the second gear 152.

Rotation of the second gear 152 causes the end effector 110 to pivot orarticulate about the pivot axis “P” (FIG. 5) relative to the firstlongitudinal axis “X1” of the elongate body 102 due to the second gear152 being non-rotatably coupled to the proximal end 116 of the endeffector 110. Upon the end effector 110 being pivoted about the pivotaxis “P,” the second longitudinal axis “X2” of the end effector 110becomes misaligned (i.e., non-parallel) with the first longitudinal axis“X1” of the elongate body 102, as shown in FIGS. 9 and 10. Continuedrotation of the second gear 152 will continue to pivot the end effector110 until the respective longitudinal axes “X1” and “X2” of the elongatebody 102 and the end effector 110 are perpendicular to one another, asshown in FIGS. 9 and 10. As can be appreciated, the second and third,articulated positions of the end effector 110 are 180 degrees apart.

The present disclosure also relates to methods of using the describedsurgical stapling instruments 10 a, 10 b to perform a surgical procedureand/or to articulate an end effector of a surgical stapling instrument.Staples may be fired from a cartridge of the end effector employing asimilar mechanism disclosed in U.S. Pat. No. 6,953,139 to Milliman etal., which has been incorporated by reference herein.

Persons skilled in the art will understand that the instruments andmethods specifically described herein and illustrated in theaccompanying drawings are non-limiting exemplary embodiments. It isenvisioned that the elements and features illustrated or described inconnection with one exemplary embodiment may be combined with theelements and features of another without departing from the scope of thepresent disclosure. As well, one skilled in the art will appreciatefurther features and advantages of the disclosure based on theabove-described embodiments. Accordingly, the disclosure is not to belimited by what has been particularly shown and described, except asindicated by the appended claims.

What is claimed is:
 1. A surgical instrument comprising: an elongatebody having a proximal end and a distal end and defining a firstlongitudinal axis; a toothed rack disposed within the elongate body andbeing movable in a direction parallel to the first longitudinal axis;and an end effector having a proximal end pivotally supported on thedistal end of the elongate body, the end effector defining a secondlongitudinal axis and supporting a gear operatively associated with therack, wherein longitudinal movement of the rack effects rotationalmovement of the gear to effect pivotal movement of the end effectorrelative to the elongate body from a first position in which the secondlongitudinal axis is aligned with the first longitudinal axis to asecond position in which the second longitudinal axis is misaligned withthe first longitudinal axis, the proximal end of the end effectordefining a first slot configured for receipt of a distal end of therack.
 2. The surgical instrument according to claim 1, furthercomprising another gear rotatably supported at the distal end of theelongate body, the gear supported on the elongate body defining a firstgear and the gear supported on the end effector defining a second gear,wherein the first gear is in meshing engagement with the rack and thesecond gear such that the first gear converts longitudinal movement ofthe rack into rotational movement of the second gear.
 3. The surgicalinstrument according to claim 2, wherein the first gear includes: abottom gear in meshing engagement with the rack; and a top gearnon-rotatably coupled to the bottom gear and in meshing engagement withthe second gear.
 4. The surgical instrument according to claim 3,wherein the bottom gear is coplanar with the rack and the top gear iscoplanar with the second gear.
 5. The surgical instrument according toclaim 3, wherein the bottom and top gears of the first gear are spacedfrom one another.
 6. The surgical instrument according to claim 3,wherein the bottom gear has a smaller diameter than a diameter of thetop gear.
 7. The surgical instrument according to claim 1, wherein theend effector is configured to rotate 180 degrees relative to theelongate body about a pivot axis extending perpendicularly relative tothe first longitudinal axis.
 8. The surgical instrument according toclaim 1, further comprising an articulation mechanism coupled to theproximal end of the elongate body and including a lever operativelycoupled to a proximal end of the rack such that rotation of the levereffects longitudinal movement of the rack.
 9. The surgical instrumentaccording to claim 1, wherein the rack is configured to movelongitudinally relative to the elongate body between an intermediateposition and a distal position, in which the distal end of the rack isdisposed within the proximal end of the end effector.
 10. The surgicalinstrument according to claim 9, wherein the end effector is in thefirst position when the rack is in the intermediate position, and theend effector is in the second position when the rack is in the distalposition.
 11. The surgical instrument according to claim 9, wherein whenthe rack is in the intermediate position the distal end of the rack isdisposed proximally of the proximal end of the end effector.
 12. Thesurgical instrument according to claim 9, wherein the rack is furtherconfigured to move to a proximal position, in which the end effector ismoved to a third position whereby the second longitudinal axis ismisaligned with the first longitudinal axis.
 13. The surgical instrumentaccording to claim 12, wherein a distal end of the end effector isdisposed on a first side of the first longitudinal axis when the endeffector is in the second position, and wherein the distal end of theend effector is disposed on a second side of the first longitudinal axiswhen the end effector is in the third position.
 14. The surgicalinstrument according to claim 9, wherein the distal end of the rackextends across and through the proximal end of the end effector when inthe distal position.
 15. The surgical instrument according to claim 9,wherein the distal end of the rack extends across first and secondopposing lateral sides of the proximal end of the end effector when inthe distal position.
 16. The surgical instrument according to claim 15,wherein the first slot is defined in the first lateral side, theproximal end of the end effector defining a second slot in the secondlateral side, such that the distal end of the rack is received withinboth of the first and second slots when in the distal position.